GI TBL 24 Flashcards
What makes up the musculotendinous sheet of the ANTEROlateral wall?
3 lateral muscle layers and their anterior aponeuroses.
The three flat muscles are the internal and external oblique and transverse abdominis (superficial to deep layer)
What cells (embryological derivative) form the musculotendinous sheet?
myoblasts and fibroblasts of the parietal mesoderm form the sheet.
Discuss the external oblique- layer formation, fiber orientation, origin/attachment.
superficial muscle layer
fibers run inferomedially from the inferior six ribs (5th-12th ribs) to the iliac crest.
Discuss the internal oblique- layer formation, fiber orientation, origin/attachment.
intermediate muscle layer
fibers run superomedially from the iliac crest to the inferior three ribs (10th-12th ribs).
Discuss the shared actions of the EXTERNAL oblique and ipsilateral/contralateral internal/external oblique. How are the shared actions accomplished?
external oblique and contralateral internal oblique form a two-bellied muscle sharing a common central aponeurosis
synergistic actions of the muscle bellies cause flexion and rotation for torsional movement of the trunk.
What muscle forms the innermost muscle layer of the abdominal wall?
Discuss said muscle fiber orientation, origin, insertion, and action.
Transverse abdominis
Contraction of its fibers, which run transversely from the iliac crest and internal surfaces of the inferior six ribs (7th-12th ribs) to the linea alba, increases intraabdominal pressure.
What forms the rectus sheath and what does it enclose?
The rectus sheath fuses in the midline to form _____.
the fused aponeuroses of the three muscle layers form the rectus sheath, which encloses the paired rectus abdominis muscles and fuses in the midline to form the linea alba.
What is the surgical relevance of the linea alba?
the linea alba is used for rapid midline incisions that are relatively bloodless and avoid major nerves.
Discuss the fiber orientation of the rectus abdominis, origin, attachment, and action.
the rectus abdominis muscles extend vertically from the pubic symphysis to the 5th to 7th costal cartilages
their contraction flexes the vertebral column, especially in the lumbar region.
Discuss nerve innervation of the anterolateral abdominal wall.
somatic afferent fibers, somatic efferent fibers, and post-synaptic sympathetic fibers of intercostal nerves T5-T11, the subcostal nerve (T12), and the iliohypogastric and ilioinguinal nerves (L1) supply the anterolateral abdominal wall.
Discuss the route taken by the abdominal aorta and its bifurcations.
the abdominal aorta bifurcates at vertebrae L4 (umbilicus is the surface indicator) into the right and left common iliac arteries that bifurcate into the external and internal iliac arteries.
Discuss the route continuation of the external iliac artery and internal iliac artery.
external iliac artery continues as the femoral artery and the internal iliac artery enters the pelvic cavity
Why does lack of muscle tone in the anterolateral wall contribute to visceroptosis and excessive lordosis?
Abdominal muscles protect and support the viscera most
effectively when they are well toned
When the anterior abdominal muscles are underdeveloped or become atrophic, as a result of
old age or insufficient exercise, they provide insufficient tonus to resist the increased weight of a protuberant abdomen on the anterior pelvis. The pelvis tilts anteriorly at the hip joints when standing (the pubis descends and the sacrum ascends) producing excessive lordosis (sway back) of the lumbar region.
Note: Visceroptosis is a condition in which the abdominal organs fall to a lower part of the abdomen.
Note: The six common causes of abdominal protrusion begin with the letter F: food, fluid, fat, feces, flatus, and fetus. Eversion of the umbilicus may be a sign of increased intra-abdominal pressure, usually resulting from ascites (abnormal accumulation of serous fluid in the peritoneal cavity), or a large mass (e.g., a tumor, a fetus, or an enlarged organ such as the liver).
Why do palpation-induced spasms of the anterolateral wall muscles provide a clinical sign of acute abdomen?
Guarding- involuntary spasms of the abdominal muscles.
Intense guarding, board-like refl exive muscular rigidity that cannot be willfully suppressed, occurs during palpation when an organ (such as the appendix) is infl amed and in itself constitutes a clinically signifi cant sign of acute abdomen.
The involuntary muscular spasms attempt to protect the viscera from pressure, which is painful when an abdominal infection is present. The common nerve supply of the skin and muscles of the wall explains why these spasms occur.
Discuss Camper’s fascia and what it is reinforced by.
fatty superficial fascia below the umbilicus is called Camper’s fascia that is reinforced by Scarpa’s fascia, a deep fascial layer formed by elastic and collagen fibers.
Discuss lymphatic drainage of Camper’s fascia.
lymphatic vessels in Camper’s fascia drain into the superficial inguinal lymph nodes.
Define the transversalis fascia what it lines.
endoabdominal fascia lines the internal surface of the musculotendinous sheet and is called the transversalis fascia where it lines the internal surface of the transverse abdominis.
Discuss the relation of the EXTRAPERITONEAL FAT to transversalis fascia.
extraperitoneal fat separates the transversalis fascia from the parietal peritoneum (i.e., mesothelium analogous to the parietal pleura of the thoracic wall).